Tone control



o t- 1935- I J. k. JOHNSON 2,018,526

TONE CONTROL Filed Sept. 8, 1952 I I3 i 77 j INVENTOR JOHN KELLY JOHNSON ATTORN EYS Patented Oct. 22, 1935 2,018,526 TONE coN'mo'i.

John Kelly Johnson, Rye, N. Y., assignor to Hazeltine Corporation Application September 8, 1932, Serial No. 632,150

4 Glaims.

This invention relates to radio receivers, and more particularly to means for varying the tone of the reproduced signal.-

' In accordance with this invention, the tone of d the reproduced signal is varied simultaneously sensitivity control and the tone control in such with the sensitivity of the receiver so that the high frequencies are reduced as the sensitivity andoverall amplification of the receiver are increased.

In a radio receiver, whenever the sensitivity is maximum, as, for instance, when operating a re ceiver equipped with a local-distance switch, with the switch in the distance position, annoying hissing sounds of the higher audio frequencies are reproduced. Furthermore, when operating a receiver at maximum sensitivity, static and other atmospheric noises of the higher audio frequencies are reproduced even when not tuned to a carrier-frequency.

The primary object oi this invention is toreduce theaudio-frequency response to the high frequencies whenever the sensitivity of the receiver is such as to produce these high audio frequencies to an objectionable extent.

It is a particular object of this invention to provide a radio receiver including means for altering the sensitivity, such as a local-distance switch, and a tone control adapted to attenuate the high audio frequencies, which shall be operative whenever the receiver is operating at maximum sensitivity.

These and further objects of theinvention will become apparent from the following description taken in connection with the accompanying drawing.

In accordance with this invention, means are provided tov receive and reproduce audioafrequency currents representative of the signal being transmitted. In the receiving means, sensitivity control means are provided, such, for instance, as a local-distance switch, by means of which the sensiti ity of the receiver may bealteredr In some portion of the audio frequency circuit a tone control arrangement is provided. Means are provided for simultaneously operating the a manner that the high audio frequencies are attenuated in the output 01' the receiver whenever the receiver is operated at high sensitivity. The sensitivity control may be of any desired type, such, for instance, as an ordinary volume control, although that shown for the purpose or illustration is a local-distance switch in which the receiver may be adjusted to have either one or two degrees of sensitivity. The tone control may be of any desired arrangement, the specific details of which constitute no part of this invention, although that shown for the purpose of illustration. is a filter composed of an audio-frequency b -pass condenser which is selectively connected in some portion of the audio-frequency circuit,. the selecting means being operated conjointly with the sensitivity control means.

When receiving distant stations, which results in the production of an abnormally high proportion of disturbing high-frequency audio sounds, the loss of fidelity, due to a tone control, is not objectionable, and it is under these circumstances that the present invention provides such a tone control. is listening to a localstation, and his desire is to have the maximum tone fidelity obtainable, the high-frequency attenuator condenser is disconnected and the signals are reproduced with maximum fidelity. 20

Supplemental means may be provided to perunit the operator to control the tone'in accord, ance with his own particular desires.

' The invention will be better understood by con-- sideration of the drawing, which shows a single figure illustrating a preferred embodiment of this invention.

,In this figure, the incoming signal is impressed upon the antenna circuit ll-l2, the antenna inductance of which is coupled in the usual manner A condenser i3 is arranged to be selectively connected in shunt with the antenna inductance 4 by meansot the double-pole, single-throw switch ll. When this condenser is in shunt with the antenna inductance,,-the sensitivity of the receiver is decreased, as the condenser l3 serves to by-pass a portion of the radio-frequency energy.

The switch It also serves to connect the audiofrequency by-pass condenser l8 and the variable resistor IS in shunt with the input of the audio- 5 frequency amplifier II. This condenser is so chosen as to by-pass the higher audio frequencies whenever it is connected in the circuit, and thus reduce or attenuatethe audio response to the higher audio frequencies. By means of the When, on the other hand, the operator 15 operator so that even when receiving distant stations the attenuation at high frequencies may be reduced.

The tone control may be provided at any point in the audio circuit and any desired filter arrangement may be substituted for the condenser shown. The specific details of the tone control arrangement shown and described constitute no part of this invention and are for the'purpose of illustration only.

Similarly, the specific details of the sensitivity control, which is in this instance represented as the usual local-distance switch, constitute nov part of this inventiomand it is to be understood that any appropriate sensitivity control may be substituted therefor.

The present invention resides in the 'combination of the sensitivity control, the tone control, and the means by which they are simultaneously operated, so that whenever the receiver is operated at maximum sensitivity, the high audio frequencies are attenuated.

Supplemental means may be provided for controlling the tone of the receiver even when the local-distance switch is in the local position and the condenser I8 is consequently disconnected from the. circuit. Such means comprise the condenser and the variable resistor 2|, by means of which the effect of the condenser upon the audio-frequency circuit may be controlled by the operator. Thus, he may reduce the response of the receiver to high audio frequencies even when receiving local stations.

In operation, whenever the sensitivity of the :receiver is increased, as, for instance, when receiving signals from distant stations, resulting in the reception of a large number of strays or atmospherics and in the generation of tube noises, etc., the tone control is simultaneously and automatically placed into operation and the resulting high audio frequencies are attenuated. When, on the other hand, the sensitivity ofthe, receiver is reduced, as when receiving local stations, in which it is desired to have maximum tone fidelity, the tone control condenser is removed from the circuit, and the signals are-reproduced with maximum fidelity.

What is claimed is: 1. In a radio receiver, the combination with.

means for receiving, detecting, amplifying and reproducing a signal-modulated carrier wave, means for altering the sensitivity of said receiver,

means for altering the tone of the reproduced signal, a signal means'for simultaneously or crating said last two means, and manually operable means connected in series with the tonealtering means for varying the effect of said tone-altering means upon the reproduced signal.

2. In a radio receiver, the combination of means for receiving, detecting, and amplifying a signal-modulated carrier wave, means for altering the sensitivity of said receiver, comprising a local-distanceswitch included in said receiving means means for altering the tone of the detected and reproduced signal, a single means for simultaneously operating said last two means, and a supplemental tone control means for controlling the tone of reproduction when the tonealtering means is inoperative.

3. In a radio receiver, the combination of means for receiving, detecting, and amplifying a signal-modulated carrier wave, means for amplifying the audio-frequency signal, means for a1 nected in a portion ofsaid audiofrequency am-.

'plifying' circuit to by-pass high audio frequencies an adjustable resistor in series with said condenser for manually controlling the effect of said condenser in' by-passing the high audio frequencies, unitary means for simultaneously operating the sensitivity-altering means and connecting said condenser in the audio-frequency circuit. and supplemental tone-control means for controlling the tone of the reproduced signal when the tone-altering means is disconnected.

4. In a radio receiver, the combination of means for receiving, detecting, andamplifying a signal-modulated carrier wave, audio-frequency amplifying means for amplifying the detected signal, means for altering the sensitivity ,of said receiver comprising a condenser selectively connected in the circuit of said receiving means to by-pass a portion of the radio-freouency energy when connected in said circuit, means for altering the tone of the detected sig-- nal comprising an audio-frequency by-pass condenser selectively connected in some portion of the audio-frequency amplifying circuit, and uni- ,tary means for simultaneously connecting said second-mentioned condenser and disconnecting said first-mentioned condenser, whereby asv the sensitivity of said receiver is increased, the high- JOHN KELLY JOHNSON.

CERTIFICATE or CORRECTION.-.

PateneNo. 2,018,526. A I e October 22. 1935.

w JOHN KELLY IOHNSON.

It is hereby certified that error appears in' the printed'spec-i fication of the- 7.

above numbered patent requiring correction as follows: Page 2, second column, line 1, claim l,- for "Signal" second occurrence, read single; and line 25, claim 3, .after lfrequencies" insert a comma; and that'thesaid Lette-rsPatent should be read with these corrections therein thatthe. some mayconform to' the record e of the casein the Patent-."Office. I 1 I Signedl nndisealedithis' zorh day of Novemben-jr Ar;.D. 

